Because Aya forced him to... In her words, since she had already given him a backdoor to the challenge, he still needed to follow proper protocol.
Before coming in, Aya taught him the movements for welcoming a challenge, the format of the sentences he should use, and the expression he should maintain on his face.
Ash was initially very resistant, after all, he is all about doing things his own way, but when under someone else's roof, one has to lower their head, especially when taking a backdoor entry, so Ash complied with what Aya said.
However, the movements he made looked extremely reluctant.
"Haha, I've been hearing your name quite a lot recently, as a new Trainer, you've not only gotten five Gym Badges in a row, but one of them is even the Golden Badge from Saffron Gym, which was only obtainable when Sabrina was the Gym Leader, your strength... just what level is it at?" Koga said meaningfully.
"Just got lucky, the Pokemon I used to defeat Sabrina wasn't one I raised, you could say it was captured by special means, as for my actual strength, wouldn't Mr. Koga find out if he battles me?" Ash waved modestly.
He's not wrong, Gengar was captured through an in-person battle, not a normal capture, and without using Gengar, his strength isn't enough to even touch Elite Level.
"Brother, didn't you set a rule at the front of the Gym? Anyone who's been active for around two months and has more than four Gym Badges can challenge the Gym without queuing, so I brought him here." Aya interjected, offering an explanation for bringing Ash and his group.
Since the Gym battle was taking place outdoors, many Trainers and onlookers had gathered on the surrounding buildings to watch the battle unfold, and the battles from the past few days had been live-streamed through onsite cameras.
Therefore, Aya bringing Ash and his group made it necessary to explain the reason, otherwise, cutting the line for no reason would undoubtedly cause public outrage, or even lead to intense criticism online.
However, with Aya's statement, many people assumed that Koga's rule was specially tailored for Ash.
After all, a Trainer who managed to get four Badges within two months can't be said to be nonexistent, but they're certainly rare, and it's quite coincidental for such a trainer to appear right after the rule was set.
As for why Koga would set this rule specifically for Ash, perhaps Koga anticipated Ash's challenge, along with his own desire to have a bout with Ash, leading him to foresee and set this rule.
And now, Ash has definitively made his way to the Fuchsia Gym.
"That's right, I set the rule, and Ash meets the criteria, so he can challenge directly. So Ash, what level of Gym battle would you like to challenge? Elite, Professional, Gym, or... Elite Level?"
Upon hearing this, Ash pondered for a while, and finally said slowly, "Let's go with Elite Level."
"Hmm, Elite Level, that's a good choice... what did you say?!" Koga nodded subconsciously, but immediately realized what Ash said, his eyes widened in surprise, his expression stunned.
"Ash must be joking, but brother is asking seriously, this isn't the time for jokes, Ash," Aya stepped in to smooth things over, not believing Ash was serious about selecting Elite Level difficulty.
Even if Ash had beaten Sabrina at Saffron Gym, that didn't mean he had Elite Level combat power, bear in mind that the Fuchsia Gym battle is a three-on-three, and choosing Elite Level difficulty means he needs to win against three Elite Level Pokemon.
Haha, being out for two months and possessing a lineup capable of combating three Elite Level Pokemon, saying such a thing would be laughable even if it was said by Leon.
"Are you planning to do a one-on-one?" Koga asked after a moment of shock, turning his gaze to Ash.
While three-on-three is indeed unlikely, one-on-one is within Ash's capability.
Never mind Ash's Trainer level, his Pokemon must be at least one Elite Level, or else it would have been impossible to defeat Sabrina.
Ash also mentioned that the Pokemon he used to defeat Sabrina was captured by special means, but regardless of the method, as long as he captured it and can command it, it's Ash's Pokemon.
So Ash does indeed have an Elite Level Pokemon, and can engage in a one-on-one Elite battle.
Gym's rules aren't fixed, if the challenger and Gym Leader agree, the number of battles can naturally be changed.
So Koga considered that Ash might want to engage in a one-on-one Elite battle, which gives Ash a decent chance at winning.
"No, I want to have a three-on-three Elite battle," Ash shook his head, once again denying Koga's assumption.
Koga lost his composure again, his face displaying a rather comical expression, looking at Ash as if he were a monster, and Aya along with the staff had similar expressions.
While some observers couldn't clearly hear the discussion between Koga and Ash from a distance, those watching the televised live broadcast could hear it loud and clear.
"This is insane, a newcomer daring to challenge Elite Level difficulty, does he think Elite Level Pokemon are as easy as those weaklings he faced before?"
"Laughable, now everyone thinks they can come and face off against the Elite. This newcomer seems to be a genius, but isn't everyone who became Elite a genius? Boasting like this in front of potential Elites, I'm curious to see how horribly this rookie will get beaten!"
"..."
Such comments were erupting in various places around Kanto and even Johto.
Koga's live stream had been pre-announced, so quite a number of people were watching on TV and computers, most of them from Kanto and Johto, with fewer from other areas, but still present.
Hence, Ash's 'arrogant' move was heard across all regions, indirectly making him famous.
...
Gary, who had already obtained the Lanyan Gym Badge, was walking down the street when his eyes inadvertently caught the TV screen nearby, and he instantly stopped, staring at the TV.
He wasn't mistaken, the guy on TV was definitely Ash!
Wait, are Gym challenges now broadcast live? If he had known, Grandpa Gary would have gone to challenge Fuchsia Gym too!
Win or lose aside, fame would have definitely skyrocketed!
Currently, the outside world only knows Ash from Pallet Town as Kanto's super rookie, with nobody aware that he, Gary, is also a super genius Trainer who has collected seven Badges after two months!
However, hearing Ash on TV challenging a three-on-three Elite match made the corner of Gary's mouth twitch, eliminating any desire to appear on TV.
Ha, what's the point of being on TV? Could he propose a three-on-three Elite battle to Koga like Ash?
What a joke, even if it was just one Elite, Koga could spin him around like a top!
He knew Ash had an Elite Level Gastly, even if they couldn't win a three-on-three match, at least Ash could showcase some strength rather than getting swept or crushed.
But him... haha, fight an Elite? Dream on!
"Ash, you've grabbed the spotlight again, I'll let you take the lead for now, but in the Quartz Conference, I'll reclaim it all... Yes, I must make sure that guy can't use Gengar, otherwise, what's the point?"
Gary was already strategizing on how to reclaim his glory at the Quartz Conference.
And he had to make sure Ash couldn't use his Elite Level Gengar.
Otherwise, let alone reclaiming his glory at the Quartz Conference, even over the next couple years, he might not achieve it.